Commercial aircraft carry millions of passengers each year. For relatively long international flights, wide-body aircraft are typically used. These aircraft include multiple passenger aisles and have considerably more space than typical so-called narrow-body aircraft. Narrow-body aircraft carry fewer passengers shorter distances, and include only a single aisle for passenger loading and unloading. Accordingly, the available space for ancillary equipment is somewhat limited on a narrow-body aircraft.
Wide-body aircraft may include full audio and video entertainment systems for passenger enjoyment during relatively long flights. Typical wide-body aircraft entertainment systems may include cabin displays, or individual seatback displays. Movies or other stored video programming is selectable by the passenger, and payment is typically made via a credit card reader at the seat. For example, U.S. Pat. No. 5,568,484 to Margis discloses a passenger entertainment system with an integrated telecommunications system. A magnetic stripe credit card reader is provided at the telephone handset and processing to approve the credit card is performed by a cabin telecommunications unit.
In addition to prerecorded video entertainment, other systems have been disclosed including a satellite receiver for live television broadcasts, such as disclosed in French Patent No. 2,652,701 and U.S. Pat. No. 5,790,175 to Sklar et al. The Sklar et al. patent also discloses such a system including an antenna and its associated steering control for receiving both RHCP and LHCP signals from direct broadcast satellite (DBS) services. The video signals for the various channels are then routed to a conventional video and audio distribution system on the aircraft which distributes live television programming to the passengers.
In addition, U.S. Pat. No. 5,801,751 also to Sklar et al. addresses the problem of an aircraft being outside of the range of satellites, by storing the programming for delayed playback, and additionally discloses two embodiments--a full system for each passenger and a single channel system for the overhead monitors for a group of passengers. The patent also discloses steering the antenna so that it is locked onto RF signals transmitted by the satellite. The antenna steering may be based upon the aircraft navigation system or a GPS receiver along with inertial reference signals.
A typical aircraft entertainment system for displaying TV broadcasts may include one or more satellite antennas, headend electronic equipment at a central location in the aircraft, a cable distribution network extending throughout the passenger cabin, and electronic demodulator and distribution modules spaced within the cabin for different groups of seats. Many systems require signal attenuators or amplifiers at predetermined distances along the cable distribution network. In addition, each passenger seat may include an armrest control and seatback display. In other words, such systems may be relatively heavy and consume valuable space on the aircraft. Space and weight are especially difficult constraints for a narrow-body aircraft.
Published European patent application No. 557,058, for example, discloses a video and audio distribution system for an aircraft wherein the analog video signals are modulated upon individual RF carriers in a relatively low frequency range, and digitized audio signals, including digitized data, are modulated upon an RF carrier of a higher frequency to avoid interference with the modulated video RF carriers. All of the video and audio signals are carried by coaxial cables to area distribution boxes. Each area distribution box, in turn, provides individual outputs to its own group of floor distribution boxes. Each output line from a floor distribution box is connected to a single line of video seat electronic boxes (VSEB). The VSEB may service up to five or more individual seats. At each seat there is a passenger control unit and a seat display unit. Each passenger control unit includes a set of channel select buttons and a pair of audio headset jacks. Each display unit includes a video tuner that receives video signals from the VSEB and controls a video display.
A typical cable distribution network within an aircraft may be somewhat similar to a conventional coaxial cable TV system. For example, U.S. Pat. No. 5,214,505 to Rabowsky et al. discloses an aircraft video distribution system including amplifiers, taps and splitters positioned at mutually distant stations and with some of the stations being interconnected by relatively long lengths of coaxial cable. A variable equalizer is provided at points in the distribution system to account for different cable losses at different frequencies. The patent also discloses microprocessor-controlled monitoring and adjustment of various amplifiers to control tilt, that is, to provide frequency slope compensation. Several stations communicate with one another by a separate communication cable or service path independent of the RF coaxial cable. The patent further discloses maintenance features including reporting the nature and location of any failure or degradation of signals to a central location for diagnostic purposes.
Service reliability is important to an aircraft in-flight entertainment system. Of course, one considerable technical challenge for an in-flight entertainment system receiving DBS signals is that the antenna must be accurately steered to track the satellite while the aircraft is in flight. Rain or other atmospheric phenomena may affect signal propagation at certain frequencies thereby further complicating accurate antenna steering and thereby adversely effecting service reliability.